Alcoholic liver disease is a common cause for morbidity and mortality in the U.S. Alcoholic steatohepatitis, the early phase of the disease, is reversible and understanding its molecular pathogenesis is essential to identify new therapeutic targets for this disease. The Wnt/beta-catenin pathway is an intracellular signaling pathway that plays an important role in normal liver development, growth, and regeneration. The main aim of this proposal is to understand the role of this pathway in the molecular pathogenesis of alcohol-induced steatohepatitis using mouse models of alcoholic liver disease. The central hypothesis being tested is that the protein beta-catenin, a key player in the Wnt signaling pathway, plays a protective role in the development of alcoholic steatohepatitis. To test this hypothesis, in Specific Aim 1, the effects of ethanol on Wnt/beta-catenin signaling will be determined both in vitro and in vivo. Ethanol-treated primary hepatocyte cultures, Kupffer cell cultures, and hepatoma cell lines will be used to investigate changes in Wnt signaling in vitro. Ethanol- fed mice will be utilized to study changes in Wnt signaling in vivo. In Specific Aim 2, the effects of loss of b- catenin on the liver with chronic ethanol feeding will be determined using liver-specific b-catenin knockout mice. Liver histology, markers of liver injury, oxidative stress, hepatic fibrosis, cytokine profile, and alterations in the expression of metabolic genes will be characterized in the livers of ethanol-fed knockout mice. In Specific Aim 3, the effect of ethanol feeding on the liver in transgenic mice expressing a stable, mutated-form of b-catenin in the liver will be investigated. These studies will provide new insights into the molecular events underlying development of alcoholic steatohepatitis. This proposal is for a five-year Mentored Career Development Award and the studies will be carried out under the primary mentorship of Dr.Satdarshan Monga at the University of Pittsburgh. The project will provide an outstanding opportunity to the principal investigator, Dr. Behari, to develop into an independent investigator in the area of alcohol-related liver disease.